1. Field of the Invention
This invention relates a method for forming a single crystalline film, and more particularly the method suitable for the fabrication of electronic devices, optical devices, integrated devices and opto-electronic integrated devices.
2. Description of the Related Art
A technique of forming a single crystalline film on a single crystalline substrate is very often employed for integrated circuits, electronics devices and optical devices. The single crystalline film is formed through an epitaxial growth using atomic and molecular beams on the single crystalline substrate.
On account of a difference in lattice constant between the single crystalline substrate and the single crystalline film and of dislocations included in the substrate itself, the film epitaxially grown on the substrate often includes many dislocations. It is preferable to eliminate dislocations because they cause the life time of the devices to be degraded and the device-characteristics to be fluctuated.
The inventor has disclosed, what is called, a micro-channel epitaxy technique in Japanese Patent Publication Kokai Hei 1-161822 and Kokoku Hei 6-105797.
Following the technique, an amorphous insulating film is formed on a single crystalline substrate and a strip opening is formed in the film to epitaxially grow a single crystalline film therein. Then, after the opening was buried by the crystalline film, the crystalline film in the opening serves as a seed for a single crystalline film growing epitaxially in a lateral direction parallel to a surface of the substrate to form the epitaxially grown single crystalline film on the amorphous film.
Most of the dislocations in the substrate do not propagate in the parallel direction in the grown single crystalline film, so that the grown single crystalline film formed on the amorphous film can have much less dislocations.
However, since a liquid phase epitaxy method has been employed in the above technique, it is difficult to form a uniform film on a large-scale substrate. Thus, the technique is not sufficient for using in a real semiconductor-manufacturing site and for realizing the above mentioned devices. Consequently, a technique to make possible a micro-channel epitaxy through a vapor phase epitaxy such as the molecular beam epitaxy (MBE), a metalorganic vapor phase epitaxy (MOVPE) or a halide source epitaxy is desired.